pannen

Great idea! You could use a capacitive sensor instead of a pushbutton (http://www.arduino.cc/playground/Code/CapacitiveSensor). Can't be cheated that easily and you don't have any mechanical parts.

Yes, it's the same stuff you get at your local electronics store, you just buy them directly from shenzen/china. I ordered a lot of components that way. Sometimes it takes some weeks for the packets to arrive. One of about 25-30 orders didn't arrive and I got my money back immediately. If you pay by paypal you're covered anyway. In Germany you don't have to pay import taxes on packets with a value under 22 Euros, so there aren't any additional costs. I never had any defects - I ordered the RFID reader from my post a few weeks ago and it works great with the arduino without any additional components and has a very good antenna. I also got 6 of the cheap servos and they're of good quality and are working flawless. Another good place to order cheap electronics directly from china is this site: http://www.dealextreme.com So get out your soldering iron

Where do you buy your components? RFID-Reader: 18$ - http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=140499984802 Servo: 3$ - http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=260687498226 LCD-Display: 4$ - http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=320537704468 Battery holder: 3$ - http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=320558885963 Aduino-Clone: 19$ - http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=250756721952 Building a cool cachebox: priceless

I have an idea for an arduino-powered traditional geocache I already posted in the arduino forum. I'd love to do this myself, but since I'm in the middle of a big city I can't find the right spot to pull this off anywhere near me where I could maintain it. Here's the idea: You make a plastic cache-container that can close with a servo from the inside like my reverse geocache. You'll add an arduino, some kind of display mounted in the lid and an rfid reader with the antenna on the bottom of the container. For power supply I'd add a 9V battery holder that can be accessed from the outside. Then you hide the cachebox in a place from where you can see two distinct landmarks (a bench, some kind of tree stump, etc.). In the cache listing you'll tell the people to bring a 9V battery. When the cacher finds the cache it won't open. They insert the 9V battery and the display says 'put me on the red mark on the bench behind you'. I have an idea for an arduino-powered traditional geocache. I'd love to do this myself, but since I'm in the middle of a big city I can't find the right spot to pull this off anywhere near me where I could maintain it. There's an rfid card glued under that spot and when the cacher puts the box there the reader sees the rfid and the display says 'Put me on the treestump 200 meters north of here - you have 40 seconds... '. A countdown from 50 begins. If the cacher does't put the box on the rfid chip in the tree stump within the 50 seconds he has to start over (put it on the bench). If he makes it the box says 'Now back to the bench, you got 35 seconds' and the countdown starts. If he makes it back to the bench in time the box opens. To close it again he has to take out the battery and put it in again or put the box on a third rfid chip. Would be real fun if you would install that somewhere where you could watch the people running around You could also add more rfid stations or make them run faster. If you find a spot where there's something like a grid with different field on the ground (like these giant chess boards in parks) you could also make out a kind of puzzle where you have to place the box on different fields with rfids buried in them due to hints on the display. Like just displaying 'A3-D5-F3' with the chess board.

It's not a Geocache according to the Groundspeak rules (a geocache has to be stationary) - So it won't get a GC-Code. I put a TB-Code on it in order to keep track of it: http://www.coord.info/TB3W7NC BTW: My box was featured on engadget: http://www.engadget.com/2011/01/12/nixie-tube-reverse-geocache-box-makes-us-long-for-the-80s-our-v/

Yes, the GPS-LED blinks while it's trying to get a fix. It it gets one within 2 minutes, the GPS-LED lights solid and it displays the distance or opening 'animation' for 8 seconds and switches off. It it can't get a fix, the Error-LED lights for 8 seconds and it switches off. The on-off switch is built with a latch relay, so it's really off when not operating. No, right now it uses 4 D cell batteries that have to be replaced when the box it reproprammed for the next user. I thought about a rechargeable battery, but then I'd have to add a charging circuit and I ran out of time.

It takes up to 90 seconds to get a good fix, but I'm only switching on the display tubes for 8 seconds when I got the fix to display the distance. That comment was about the battery drain of the tubes. The circuit needs much less energy without them.

The electronics draw 500mA with the tubes on but I'm just switching them on for 8 seconds per fix and the battery has 6000 mAh so it should be enough to find the target even if you need a lot of fixes. I just have a unreadable paper with my drawn schematics, but there are plenty of schematics for nixie tube clocks on the net. The hardest part is getting 180V for them, the rest is just transistors or a special driver ic for the 10 kathode pins of the tube. I also used a 4 bit binary counter for every tube because I ran out of output pins on the arduino atmel board I used.

Oh, and it wasn't that expensive. The electronics are about 50 euros and the used army box 10 euros. A friend did the cutting of the metal and I painted it myself. I spent a lot time with soldering and programming but I like doing that kind of things in my spare time

Ok, it works like this: I'm programming it with the coordinates of a nice place to visit and I'll put a present for a friend in it. I'll give it to the friend on his birthday in two weeks. He'll wonder what that is and why it doesn't open. Then he'll press the button and it will display a number like 124. Because he's pretty bright and there's a gps antenna on it he'll try it elsewhere and it'll display another number (like 157). He'll figure out that this is a distance and with some measurements and a map he can trangulate the target. He'll drive there and can circle the target until he's within 250 meters distance. Then the box opens when he presses the button. He'll find his present inside and the instructions for entering new coordinates via usb. Now he'll reprogram it with coordinates that he wants somebody to go to and pass the box with a new present inside to that person. And on and on. Because the box is moving it can't be a geocache according to groundspeaks guidelines. That's why it's just a trackable.

PS: Figuing out what the numbers mean is part of the challenge

It's the distance in km (I'm in Germany). The tubes can display a decimal point, so when the distance is below 100km the precision is 100 meters and below 10km it's 10 meters. Precise enough to triangulate the target when you press the button at a few places that are far enough apart.

It's described on the tracking page but in a nutshell: It's a box that opens only at a certain place.

Hi, I just finished building my first reverse geocache that I mentioned in this forum before. It shall be passed on from person to person so I build it as tough as possible. I used an LED display at first, but that seemed a bit boring, so I used nixie display tubes with a custom built controller. It's also trackable and there's a description on it's page : http://www.coord.info/TB3W7NC The tracking code is stamped to the bottom of the case.

The case is finished, here's a pic: It turned out exactly as I imagined it Here you'll see the locking mechanism (a servo that actuates two metal rods) Now I have to give it a nice painting and put some text next to the status leds (above the gps antenna and the display tubes). I bought a geopin and I'm planning paint the tracking number on the box (with letter stencils). For the painting I'm thinking about leaving the base color as is and painting the raised edge of the lid in yellow/black diagonal stripes. The gps antenna, the lettering and the brackets red like the button. Any other suggestions?

Well, I think I have to make it a trackable. The only thing that bothers me is, that you cant drop a trackable in another trackable, but that can be handled in the log texts. I think I will screw a tb dogtag on the outside of the cache, so people can log 'discovered' entries. To clarify the type of cache: Its a metal box (a french army medic box) that contains a microcontroller, a gps module and a display. In my case the display are 3 nixie tubes (display tubes from the 60s). All you see when the box is closed is a button and the tubes. When you press the button it tries to get a gps fix while the tubes show a countdown. If it can't get a fix (indoors) an error led lights for 5 seconds and it switches off. If it gets a fix it shows the distance to the target coordinates (down to 0,01 km precision due to the possibility to display a comma on the tubes I used). If it's within 500 meters of the target coordinates the box opens with a buildin servo. The opener can then program new coordinates (via a computer and usb), put some kind of present in it and pass it on to a friend. I can't provide photos right now, because it is with someone who's cuts out the holes in the case, but it'll look like some kind of 60s James Bond suitcase nuke, so you can't get it on a plane I'm building it for the 30th birthday of a geonut friend.

Hi, I'm currently building a reverse geocache (a box that will open at a certain position). It will be very robust (steel casing), reprogrammable by the one who gets it to the right place and rechargeable. So it shall pass from cacher to cacher. Can I greate a geocache listing for that or shall I just buy a travelbug/trackme button and put the code on the box?